Gravitational form factors of $N(1535)$ in QCD

TL;DR

This paper computes the gravitational form factors of the excited nucleon state N(1535) using light cone QCD sum rules, providing insights into its internal structure, pressure, and energy density.

Contribution

It introduces a novel calculation of N(1535)'s gravitational form factors via LCSR, including transition form factors and mechanical properties.

Findings

Gravitational form factors are well described by multipole fits.

Calculated pressure and energy density at N(1535) center.

Estimated the mechanical radius of N(1535).

Abstract

We calculate the gravitational form factors of the excited $N(1535)$ state with the quantum numbers $I(J^P)=\frac{1}{2}(\frac{1}{2}^-)$ via light cone QCD sum rules (LCSR). To this end, we consider the quark part of the energy-momentum tensor (EMT) current and use the general form of the nucleon's interpolating field as well as the distribution amplitudes (DAs) of $N(1535)$. As both the nucleon and $N(1535)$ couple to the same current, the $N(1535) \rightarrow N$ gravitational transition form factors are entered to the calculations as the main input parameters. First we revisit the transitional gravitational form factors of $N(1535) \rightarrow N$, then extract the values of the form factors of the $N(1535)$ excited state. We observe that the gravitational form factors of $N(1535)$ in terms of $Q^2$ are well described by the multipole fit function. As a byproduct, we also calculate the pressure and energy density at the center of $N(1535)$ and estimate its mechanical radius.